Method of forming meltblown webs containing particles

ABSTRACT

A method of forming a meltblown web having meltblown fibers and particles is provided. The particles are heated to a temperature approximating that of the meltblown fibers as they are being extruded. As a portion of any heated particle impacts the skin of one or more solidifying meltblown fibers, that portion of any heated particle penetrates into one or more solidifying particles. Although a portion of any particle becomes embedded in and retained by one or more meltblown fibers, such surface penetration is generally slight desirably leaving a substantial amount of surface area of any particle available for interaction with any medium to which a web may be exposed.

BACKGROUND OF THE INVENTION

[0001] This invention relates to methods of forming meltblown webs andin particular to methods of forming meltblown webs containing meltblownfibers and particulate material.

[0002] It has been desired to provide a method of formingparticle-containing meltblown webs for a variety of purposes, wherein apredetermined amount of particles is held in the web while minimizingthe amount of “dusting” (i.e., particles undesirably dropping out of theweb) the web may suffer.

[0003] Various approaches to retaining particles within a web have beenproposed. One such approach discloses a self-supporting durable flexibleconformable low-pressure-drop porous sheet product that contains auniform three-dimensional arrangement of discrete particles. The sheetproduct includes, in addition to the particles, a web of meltblownfibers in which the particles are uniformly dispersed. The particles arephysically held, such as by mechanical entanglement, in the web eventhough there is only point contact between the meltblown fibers and theparticles. (“Point contact” occurs when preformed bodies abut oneanother. It is distinguished from “area contact,” such as results when aliquid material is deposited against a substrate, flows over thesubstrate, and then hardens in place.) Even though the particles aremechanically entangled within the interstices of the web, a portion ofthe particles still undesirably drop out of the web during handling.

[0004] Another approach discloses using adhesive polymers for formingthe meltblown web. In addition to being physically entrapped in the web,the particles of this approach are also adhered to the surfaces of themeltblown fibers. Even though this may be viewed as an improvement overretaining particles within a web by point contact, this approachaccomplishes its objective with the use of expensive adhesive polymers.

[0005] For the foregoing reasons, there is a need for an improved methodof forming meltblown webs having particles substantially uniformly andhomogeneously dispersed therethrough and retained therein by more thanmere point contact or mechanical entanglement, wherein dusting issubstantially eliminated without the addition of expensive adhesivepolymers.

SUMMARY OF THE INVENTION

[0006] The present invention is directed to an improved method offorming meltblown webs having particles substantially uniformly andhomogeneously dispersed therethrough that satisfies the need tosubstantially eliminate dusting without the addition of expensiveadhesive polymers.

[0007] One embodiment of the present invention provides for a method offorming a meltblown web having at least one layer, the method includingforming a first primary stream containing meltblown fibers. A firstsecondary stream is formed containing staple fibers and merged with thefirst primary stream so that the first primary stream includes thestaple fibers entangled with the meltblown fibers. Thereafter, the firstprimary stream including the staple fibers entangled with the meltblownfibers is directed onto a moving forming surface to form a first layerhaving the staple fibers entangled with the meltblown fibers. After thefirst layer is formed, this embodiment of the invention provides forforming at least one particle-containing layer by forming a secondprimary stream having meltblown fibers. A first tertiary stream isformed containing particles and merged with the second primary stream sothat the second primary stream contains particle-containing meltblownfibers. A second secondary stream is formed containing staple fibers andmerged with the second primary stream so that the second primary streamincludes the staple fibers entangled with the particle-containingmeltblown fibers. Thereafter, the second primary stream including thestaple fibers entangled with the particle-containing meltblown fibers isdirected onto the first layer on the moving forming surface to form asecond layer having the staple fibers entangled with theparticle-containing meltblown fibers.

[0008] An alternative embodiment of the present invention provides forthe formation of a meltblown web having at least one layer, the methodincluding forming a primary stream of meltblown fibers. A tertiarystream containing particles is formed and merged with the primary streamso that the primary stream includes particle-containing meltblownfibers. Thereafter, the primary stream having particle-containingmeltblown fibers is directed onto a moving forming surface to form alayer including the particle-containing meltblown fibers.

[0009] Still another embodiment of the present invention provides forforming a meltblown web having at least one layer, the method includingforming a primary stream containing meltblown fibers. A tertiary streamcontaining particles is formed and merged with tie primary stream sothat the primary stream includes particle-containing meltblown fibers. Asecondary stream having staple fibers is formed and merged with theprimary stream so that the primary stream includes staple fibersentangled with the particle-containing meltblown fibers. Thereafter, theprimary stream having the staple fibers entangled with theparticle-containing meltblown fibers is directed onto a moving formingsurface to form a layer having the staple fibers entangled with theparticle-containing meltblown fibers.

DRAWINGS

[0010] The foregoing and other features, aspects and advantages of thepresent invention will become better understood with regard to thefollowing description, appended claims and accompanying drawings where:

[0011]FIG. 1 illustrates a forming apparatus having two units forformation of meltblown fibers with the downstream unit additionallyhaving provision for application of particles.

[0012]FIG. 2 illustrates a forming apparatus having three units forformation of meltblown fibers with the two downstream units additionallyhaving provision for application of particles.

[0013]FIG. 3 illustrates a cross-section of a coherent integratedtwo-layered web of the present invention in which one layer of the webincludes particles.

[0014]FIG. 4 illustrates a cross-section of a coherent integratedthree-layered web of the present invention in which two layers of theweb include particles.

[0015]FIG. 5 illustrates a cross-section of a coherent integratedthree-layered web of the present invention in which one layer of the webincludes particles.

[0016]FIG. 6 illustrates an alternate embodiment of a forming apparatusin which the web is provided with embossing and combined with a carriersheet.

[0017]FIG. 7 illustrates a view of an absorbent article having a web ofthe invention.

[0018]FIG. 8 illustrates a cross-section of the absorbent article ofFIG. 7 taken along line 8-8 of FIG. 7.

[0019]FIG. 9 illustrates a perspective partially broken-away view of analternate absorbent article having a web of the invention.

[0020]FIG. 10 illustrates a too view of an absorbent article having aweb of the invention showing longitudinally-embossed lines and acontinuous peripheral seal located inward from the periphery of theabsorbent article.

[0021]FIG. 11 illustrates an enlarged cross-sectional view of asolidifying thermoplastic polymeric meltblown fiber.

[0022]FIG. 12 illustrates an enlarged view of a particle retained withina web of the present invention by surface penetration into more than onemeltblown fiber.

[0023]FIG. 13 illustrates an enlarged view of a particle retained withina web of the present invention by surface penetration into at least onemeltblown fiber.

[0024]FIG. 14 is a scanning electron microscope photograph, at amagnification level of 10×, illustrating an example of the surfacepenetration of a particle, having a diameter of about 20 to about 300microns, into one or more meltblown fibers of a coform web of thepresent invention.

[0025]FIG. 15 is a scanning electron microscope photograph, at amagnification level of 10×, illustrating an example of the surfacepenetration of a particle, having a diameter of about 20 to about 300microns, into one or more meltblown fibers of a coform web of thepresent invention.

[0026]FIG. 16 is a scanning electron microscope photograph, at amagnification level of 10×, illustrating an example of the surfacepenetration of a particle, having a diameter of about 20 to about 300microns, into one or more meltblown fibers of a coform web of thepresent invention.

[0027]FIG. 17 is a scanning electron microscope photograph, at amagnification level of 10×, illustrating an example of the surfacepenetration of a particle, having a diameter of about 20 to about 300microns, into one or more meltblown fibers of a coform web of thepresent invention.

[0028]FIG. 18 is a scanning electron microscope photograph, at amagnification level of 10×, illustrating an example of the surfacepenetration of a particle, having a diameter of about 20 to about 300microns, into one or more meltblown fibers of a coform web of thepresent invention.

[0029]FIG. 19 is a scanning electron microscope photograph, at amagnification level of 1033 , illustrating an example of the surfacepenetration of a particle, having a diameter of about 5 to about 25microns, into one or more meltblown fibers of a coform web of thepresent invention.

DESCRIPTION OF THE INVENTION

[0030] The meltblown webs formed according to the methods of the presentinvention generally include at least one layer having meltblown fibersand particles.

[0031] As used herein, the term “meltblown fibers” means fibers formedby extruding a molten thermoplastic material through a plurality offine, usually circular, die capillaries as molten threads or filamentsinto a high velocity stream of heated gas, usually air, which attenuatesthe filaments of molten thermoplastic material to reduce their diameter.Thereafter, the meltblown fibers are carried by the high velocity gasstream and deposited on a collecting surface to form a web of randomlydisbursed meltblown fibers. Meltblowing is generally described, forexample, in U.S. Pat. No. 3,849,241 to Buntin, U.S. Pat. No. 4,307,143to Meitner, et al., and U.S. Pat. No. 4,707,398 to Wisneski et al., eachof which is incorporated herein by reference.

[0032] In a typical meltblowing process, an extruded filament or fibergenerally begins the process of cooling or quenching upon exiting from aforming die. As the individual meltblown fiber cools, it thus beginssolidifying. The solidification process typically begins at the exteriorof the meltblown fiber and moves toward the center of the meltblownfiber. As the meltblown fiber cools, it develops a surface or skin 700,as illustrated in FIG. 11. Although a skin may be present, there usuallyremains a molten or semi-molten inner core 702 until the core of themeltblown fiber cools and reaches its solidification temperature. Knownmethods of incorporating particulate material into a meltblown webprovide for the introduction of particulate material at about roomtemperature into a stream of meltblown fibers. Absent adhesive polymers,this room temperature particulate material is maintained in anyresulting meltblown web by either point contact or mechanicalentanglement with the meltblown fibers. While both point contact andmechanical entanglement are somewhat effective at maintaining a portionof the particulate material in the web, there remains a portion of theparticulate material that is neither in sufficient point contact withthe meltblown fibers nor sufficiently mechanically entangled in themeltblown fibers and thus either remains fugitive or easily becomesfugitive upon handling of the web. As a result of a portion of theparticulate material remaining fugitive or easily becoming fugitive,these webs suffer from the problem of dusting. Alternatively, whereadhesive polymers are used, the particulate material added at roomtemperature is maintained in any web by adhering to the surface of themeltblown fibers. Although the use of adhesive polymers substantiallyreduces dusting, adhesive polymers are relatively expensive whencompared to nonadhesive-containing polymers.

[0033] Unlike situations where the particulate material is maintainedwithin a meltblown web by point contact or mechanical entanglement, thepresent invention provides for an improved and heretofore unknown methodof retaining particles in meltblown webs which substantially eliminatesdusting without the use of expensive adhesive polymers. This novelinvention provides for using any heat-stable particle that can withstandthe force of impact with the skin of one or more meltblown fibers andyet substantially maintain its particle integrity. (The term“heat-stable”, as used herein, generally refers to any particle whosephysical, chemical or other properties remain unchanged as a result ofheat encountered by the particle.) While not desiring to be bound by anyparticular theory, it is believed that by heating the particles to atemperature approximating that of the fibers being extruded from aforming die, a portion of each particle generally impacts and penetratesinto the skin of one or more meltblown fibers. As it thus penetratesinto one or more solidifying meltblown fibers, that portion of theheated particle becomes embedded in and retained by one or moresolidifying meltblown fibers. Although a portion of the particle becomesembedded in and retained by one or more meltblown fibers, such “surfacepenetration” of the particle into one or more meltblown fibers isgenerally slight desirable leaving a substantial amount of the surfacearea of the particle available for interaction with any medium to whicha web of this invention may be exposed. FIGS. 12 through 19 illustrateexamples of the surface penetration of a variety of one or moreparticles into one or more meltblown fibers.

[0034] Referring now to FIG. 1, a forming apparatus, generally indicatedas 20, is illustrated as including two meltblown units, 30 and 130, anda movable foraminous belt apparatus, generally indicated as 60. Thefirst meltblown unit 30 includes a forming die 32 having a die tip 33and a pair of ducts 34 and 36. A material supply and delivery device 38delivers polymer to extruder 40 for delivery to the forming die 32. Afirst primary stream 42 including meltblown fibers is formed by a knownmeltblowing technique, such as is described in U.S. Pat. No. 4,100,324,issued Jul. 11, 1973, to Anderson et al., which is incorporated hereinby reference. Basically, the method of formation involves extruding amolten polymeric material through the forming die 32 into streams ofpolymer and attenuating the polymer streams by converging flows ofheated gas, usually air, supplied through ducts 34 and 36.

[0035] A first secondary stream 44 including individualized wood orother staple fibers is formed and merged into the first primary stream42 including meltblown fibers so as to entangle the individualized woodfibers with the meltblown fibers in a single step. The individualizedwood fibers typically have a length of about 0.5 to about 10 millimetersand a length to maximum width ratio of about 10:1 to about 400:1. Atypical cross-section of an individualized wood fiber has an irregularwidth of about 10 microns and a thickness of about 5 microns. In theillustrated forming apparatus, the first secondary stream 44 is formedby a pulp sheet divellicating apparatus 52 of the first meltblown unit30. (The pulp sheet divellicating apparatuses described herein are ofthe type described in U.S. Pat. No. 3,793,678, issued Feb. 26, 1974, toAppel, which is incorporated herein by reference.) The divellicatingapparatus 52 includes a conventional picker roll 46 having picking teethfor divellicatina wood pulp sheets 48 into individualized wood fibers.The wood pulp sheets 48 are fed radially along a picker roll radius tothe picker roll 46. It is the teeth of the picker roll 46 thatdivellicate the wood pulp sheets 48 into individualized wood fibers. Theresulting individualized wood fibers are conveyed toward the firstprimary stream 42 through a forming duct 5O. A passageway 54 providesprocess gas, usually air, to the picker roll 46 in sufficient quantityto serve as a medium for convevyng the individualized wood fibersthrough the forming duct 50 at a velocity approaching that of the pickerteeth. The process gas may be supplied by conventional means such as ablower, not shown. It has been found that in order to avoid significantfiber clumping or agglomeration, generally referred to as fiberfloccing, the individualized wood fibers should be conveyed through theforming duct 50 at substantially the same velocity at which they leavethe picker teeth after separation from the wood pulp sheets 48. Theapparatus described for formation of a web of meltblown fibers havingwood fibers entangled therein, such web now referred to as coform, isknown and is more fully described in the previously referenced U.S. Pat.No. 4,100,324, issued Jul. 11, 1978, to Anderson et al. The firstprimary stream 42, including wood fibers entangled therein from thefirst secondary stream 44, is then directed onto a moving formingsurface 62 that passes beneath the forming die 32. The moving formingsurface 62 is provided with suction devices 64 and 66 driven by blowers68 and 70 that withdraw gas from beneath the moving forming surface 62and provide for uniform laydown of the entangled meltblown fibers andwood fibers onto the moving forming surface. The moving forming surface62 is desirably a permeable belt. In addition to being supported by afirst roll 72, the moving forming surface 62 is also supported by asecond roll 74. While illustrated with two suction devices, the numberand size of the suction devices below the moving forming surface may bevaried in any suitable manner well known in the art. Further, themovable foraminous belt apparatus 60 may be provided with dust collectordevices, not shown, to prevent the escape of any particles and fibers tothe atmosphere.

[0036] As illustrated in FIG. 1, a first meltblown unit 30 lays down alayer of meltblown fibers having wood or other staple fibers entangledtherein as a first layer 80. This first layer 80 passes beneath a secondmeltblown unit 130 where a second layer 82 is placed thereon and joinedto the first layer 80. The second layer 82 is formed by the secondmeltblown unit 130. The second meltblown unit includes an extruder 140fed by a material supply and delivery device 138. The extruder 140 feedsto a forming die 132, that is generally similar to the forming die 32 ofthe first meltblown unit 30, in that the forming die 132 of the secondmeltblown unit 130 has a die tip 133 and a pair of ducts 134 and 136through which streams of heated gas, usually air, are supplied to asecond primary stream 142. As the as streams from the ducts 134 and 136merge and entrain the extruded fibers in the second primary stream 142,the extruded fibers are meltblown into meltblown fibers. The secondmeltblown unit 130, however, differs from that of the first meltblownunit 30 in that there additionally is provided a source of particlesgenerally indicated as a particle supply unit 160 including a storagehopper 162, having a feed device 164 leading to a source of highvelocity heated gas 166, usually air, and a feeder duct 168 providing afirst tertiary stream 170 of heated particles to merge with the secondprimary stream 142. Upon merging with the second primary stream 142,portions of the heated particles from the first tertiary stream impactand penetrate into the skin of one or more solidifying meltblown fibersand become embedded in and retained by one or more meltblown fibers. Theresulting particle-containing meltblown fibers are subsequentlyentangled with individualized wood fibers supplied by a second secondarystream 144 exiting through a forming duct 150 from a divellicatingapparatus 152 of the second meltblown unit 130 and merging with thesecond primary stream 142. In the divellicating apparatus 152, thepicker roll 146 rotates and divellicates the wood pulp sheets 148 asthey are unrolled from a pulp supply roll 149. The wood pulp sheets aredivellicated and passed through the forming duct 150 and merged with thesecond primary stream 142. Process gas, usually air, is supplied througha passageway 154 of the divellicating apparatus 152. The second primarystream 142, now having the wood fibers entangled with theparticle-containing meltblown fibers, is then directed as a second layer82 onto the first layer 80 at a laydown point 165. A suction device 66aids in laydown. Some of the meltblown fibers and wood fibers of thesecond layer 82, when laid down, become somewhat intermingled withmeltblown fibers and wood fibers of the first layer 80 along a formationline 85. This intermingling is such that an integrated coherenttwo-layered web is formed suitable for processing and use purposes.However, should the first layer 80 and the second layer 82 be pulledapart, they will generally separate on the formation line 85. Afterleaving the first roll 72, the two-layered web may be further processedby known means such as cutters and stackers, not shown. Moving formingsurface 62, in addition to being supported by the first roll 72, is alsosupported by the second roll 74.

[0037] The apparatus of FIG. 2 is a modified embodiment of the apparatusof FIG. 1 in which the first meltblown unit 30 and the second meltblownunit 130 are placed above a moving forming surface 62. Below the movingforming surface are located at least 3 suction devices 64, 66 and 169.In addition to the first and second meltblown units, there is now athird meltblown unit 230. This third meltblown unit 230 also includes,as the first and second meltblown units do, an extruder 240 fed by amaterial supply and delivery device 238, leading to a forming die 232.The forming die 232 has therein a die tip 233 and a pair of ducts 234and 236 through which streams of heated gas, usually air, are suppliedto a third primary stream 242. As the gas streams from the ducts 234 and236 merge and entrain the extruded fibers in the third primary stream242, the extruded fibers are meltblown into meltblown fibers. Like thesecond meltblown unit 130, the third meltblown unit 230 differs fromthat of the first meltblown unit 30 in that there additionally isprovided a source of particles generally indicated as a particle supplyunit 260 including a storage hopper 262, having a feed device 264leading to a source of high velocity heated gas 266, usually air, and afeeder duct 268 providing a second tertiary stream 270 of heatedparticles to merge with the third primary stream 242. Upon merging thesecond tertiary stream 270 with the third primary stream 242, portionsof the heated particles impact and penetrate into the skin of one ormore solidifying meltblown fibers and become embedded in and retained byone or more meltblown fibers. The resulting particle-containingmeltblown fibers are subsequently entangled with individualized woodfibers supplied by a third secondary stream 244 exiting through aforming duct 250 from a divellicating apparatus 252 of the thirdmeltblown unit 230 and merging with the third primary stream 242. In thedivellicating apparatus 252, the picker roll 246 rotates anddivellicates the wood pulp sheets 248 as they are unrolled from a pulpsupply roll 249. The pulp sheets are divellicated and passed through theforming duct 250 and merged with the third primary stream 242. Processgas, usually air, is supplied through a passageway 254 of thedivellicating apparatus 252. In FIG. 2, a first layer 80 is laid down bythe first meltblown unit 30. A second layer 82, containing particles, issourced from the second meltblown unit 130, and a third layer 84, thatis sourced from the third meltblown unit 230, are laid down. Some of themeltblown fibers and wood fibers of the second layer 82, when laid down,become somewhat intermingled with the meltblown fibers and wood fibersof the first layer 80 along a formation line 85. Some of the meltblownfibers and wood fibers of the third layer 84, when laid down, becomesomewhat intermingled with the meltblown fibers and wood fibers of thesecond layer 82 along a formation line 85′. This intermingling is suchthat an integrated coherent three-layered web 89 is formed suitable forprocessing and use purposes. However, should the first layer 80 and thesecond layer 82 be pulled apart, they will generally separate on theformation line 85. Similarly, should the second layer 82 and the thirdlayer 84 be pulled apart, they will generally separate on the formationline 85′. After leaving the forming apparatus 20, the coherentintegrated three-layered web 89 may; be treated by conventional meanssuch as cutters and stackers to prepare it for use in an absorbentarticle. Consequently, the forming apparatus as illustrated in FIG. 2 iscapable of forming a meltblown webs with particles in either or both ofthe second and third layers or with only the second layer containingparticles if the particle supply unit 260 is not operated.

[0038] Because the meltblown fibers are typically much longer, thinner,limper and more flexible than the wood fibers, the meltblown fiberstwist around and entangle the relatively short, thick and stiff woodfibers as soon as the two fiber streams merge. This entanglementinterconnects the two different types of fibers with strong, persistentinter-fiber attachments without any significant molecular, adhesive orhydrogen bonds. In the resulting matrix, the meltblown fibers retain ahigh degree of flexibility, with many of the meltblown fibers beingspaced apart by engagement with the comparatively stiff wood fibers. Theentangled wood fibers are free to change their orientation when thematrix is subjected to various types of distorting forces, but theelasticity and resiliency of the meltblown fiber network tends to returnthe wood fibers to their original positions when the distorting forcesare removed. A coherent integrated web is formed substantially by themechanical entanglement and intermingling of the two different fibers.

[0039] This invention has been described with the formation of a two- orthree-layered web. However, it is also within the invention to formcoform webs having only a single layer as well as coform webs havingmore than three layers. For example, the forming apparatus asillustrated in FIG. 1 is capable of forming single-layer coform websincluding particles if the first meltblown unit 30 is not operated.Consequently. it is also within the present invention that webs couldhave a single layer containing particles, or include multiple layershaving one or more layers containing particles in a variety ofmulti-layered configurations.

[0040]FIG. 3 is illustrative of a cross-section through a coherentintegrated two-layered web such as formed by the method and apparatus asillustrated by FIG. 1. A first layer 80 includes wood fibers entangledwith nonparticle-containing meltblown fibers. A second layer 82 includeswood fibers entangled with particle-containing meltblown fibers. Theparticles 86 are also illustrated in FIG. 3. A formation line 85 of thefirst layer 80 and the second layer 82 is somewhat irregular as some ofthe meltblown fibers and wood fibers from each layer are intermingled.

[0041]FIG. 4 is illustrative of a cross-section through a coherentintegrated three-layered web 89 such as may be formed by the method andapparatus of FIG. 2. As illustrated in the cross-section, a first layer80 includes wood fibers entangled with nonparticle-containing meltblownfibers. A second layer 82 and a third layer 84 each include wood fibersentangled with particle-containing meltblown fibers. The particles 86are also illustrated in FIG. 4. A formation line 85, between the firstlayer 80 and the second layer 82, is somewhat irregular as some of themeltblown fibers and wood fibers from the first and second layers areintermingled. Similarly, a formation line 85′, between the second layer82 and the third layer 84, is somewhat irregular as some of themeltblown fibers and wood fibers from the second and third layers areintermingled.

[0042]FIG. 5 illustrates an alternate embodiment of a meltblown webformed in accordance with the invention. In FIG. 5, a coherentintegrated web having three layers is illustrated. A first layer 80 anda third layer 84 include wood fibers entangled withnonparticle-containing meltblown fibers. A second layer 82 includes woodfibers entangled with particle-containing meltblown fibers. Theparticles 86 are also illustrated in FIG. 5. A formation line 85,between the first layer 80 and the second layer 82, is somewhatirregular as some of the meltblown fibers and wood fibers from the firstand second layers are intermingled. Similarly, a formation line 85′,between the second layer 82 and the third layer 84, is somewhatirregular as some of the meltblown fibers and wood fibers from thesecond and third layers are intermingled. The structure of this web hasthe advantage that the particles are not exposed on either exteriorsurface of the web.

[0043]FIG. 6 illustrates a forming apparatus such as previouslyillustrated in FIG. 1, but having some of the various optionalperipheral devices that may be included with a forming apparatus inaccordance with embodiments of the present invention. A base sheet 410may be placed onto a moving forming surface 62 prior to application of afirst layer 80 of a layered web 420. The base sheet 410 ordinarily wouldbe a pervious sheet such as a spunbonded fabric sheet that would notinterfere with gas flow through the moving forming surface 62. Thepervious material would be applied from a roll 416 passing under anapplicator roll 418 onto the moving forming surface 62. If it is desiredto improve the strength of the layered web 420, it may be embossedeither ultrasonically or at an elevated temperature so that thethermoplastic meltblown fibers are flattened into a film-like structurein the embossed areas. This film-like structure functions to hold thewood fibers more rigidly in place in the embossed areas. Thus, in theillustrative apparatus of FIG. 6, the layered web 420 is passed throughan ultrasonic embossing station having an ultrasonic calendering head422 vibrating against a patterned anvil roll 424. The embossingconditions (e.g., pressure, speed, power input) as well as the embossingpattern may be selected to provide the desired characteristics to theweb. An intermittent pattern is desired with the area of the weboccupied by the embossed areas, after passing through the embossing nip,being about 5 to about 50 percent of the surface area of the web,although the particular embossing conditions for any given material willdepend on the composition of the material. It is also known to carry onembossing by the use of heated patterned embossing rolls. In addition toimproving the strength of the web, the embossing process also improvesthe appearance of the web. It is further possible to apply a top sheet430 to the layered web 420. The top sheet may be either a pervioussheet, an impervious layer, or another absorbent material. The top sheet430 is applied from a roll 432 under an applicator roll 434. It also maybe desirable to apply a carrier or bottom sheet 440 beneath the layeredweb 420. This carrier or bottom sheet may be particularly desirable if aforming sheet is not used as it will aid in handling of the web and thenmay be discarded. Thus, it can be readily appreciated that the presentinvention uniquely provides a variety of webs having one or more layers.It can also be readily appreciated that such webs could also have asingle layer containing particles or include multiple layers having oneor more layers containing particles in a variety of multi-layeredconfigurations.

[0044] The composition of a layer having meltblown fibers and woodfibers, and the composition of a layer having meltblown fibers, woodfibers and particles may be varied over a wide range. The gas-forming ofmeltblown fibers and wood fibers in the manner described herein resultsin a web commonly called coform. This coform web may vary between about10 percent meltblown fibers and about 90 percent wood fibers, and about90 percent meltblown fibers and about 10 percent wood fibers. Generally,there is also a surfactant that is added to the web to aid in wetting ofthe polymer.

[0045] A wide variety of thermoplastic fiber-forming polymers are usefulin forming the meltblown fibers, so that webs can be fashioned withdifferent physical properties by the appropriate selection of polymersor combinations thereof. Among the many useful thermoplasticfiber-forming polymers, polyolefins such as polypropylene andpolyethylene, polyamides, polyesters such as polyethylene terephthalate,and thermoplastic elastomers such as polyurethanes are anticipated tofind the most widespread use in the preparation of the webs describedherein.

[0046] The staple fiber blown into the coform may be any fiber thatimproves the absorbency or other property of the coform. Suitable staplefibers include polyester fibers, nylon fibers, cotton fibers and woodfibers. The preferred fiber is a wood fiber as the wood fibers formedfrom pulp are of desired size, low in cost and of high absorbency.

[0047] By “particle,” “particles,” “particulate,” “particulates” and thelike, it is meant that the particulate material is generally in the formof discrete units. The particles can comprise granules, pulverulents,powders or spheres. Thus, the particles may have any desired shape thatwould allow a portion of each heated particle to slightly penetrate intoone or more solidifying meltblown fibers in accordance with the presentinvention. Desired particle shapes include, for example, cubic,rod-like, polyhedral, spherical or semi-spherical, rounded orsemi-rounded, angular, irregular, etc. Shapes having a large greatestdimension/smallest dimension ratio, like, needles, fibers and flakes,are also contemplated for use herein. The desired shaped particles maybe coated (gel-coated, protein coated and the like having a particulatecore, a porous solid core, a solid core, a semi-solid core, a liquidcore, a semi-liquid core, a gaseous core, a semi-gaseous core orcombinations thereof) or uncoated (porous solid, solid, semi-solid andthe like). It should be noted that more than one kind of particle may beused in some webs of the invention, either in mixture or in differentlayers. The use of “particle” and “particulate” may also describe anagglomeration comprising more than one particle, particulate or thelike.

[0048] A wide variety of particles capable of slightly penetrating intoone or more solidifying meltblown fibers in accordance with the presentinvention have utility in a three-dimensional arrangement in which theycan interact with (for example, chemically or physically react with, orphysically contact and modify or be modified by) a medium to which theparticles are exposed. Included among the variety of particles havingutilitivy in the present invention are superabsorbents. Thesuperabsorbent material suitable for incorporation in variousembodiments of the present invention may be any superabsorbents thatwill maintain its particle integrity during the meltblowing process andexhibit good storage, handling, and resistance to gel-blockingproperties. Typical of such superabsorbent materials are thewater-insoluble hydrocolloidal particles derived from starches that willswell, but not dissolve when exposed to water. Also suitable for variousembodiments of the invention are those superabsorbents formed fromhydrolyzed cross-linked polyacrylamides, polyacrylates, polymers ofacrylic polymers, or their copolymers. Such materials, when lightlycross-linked, are insoluble and, when dry, are solids that may be heatedand blown in a gas stream, and maintain their integrity when impactingone or more solidifying meltblown fibers.

[0049] Also included within the scope and spirit of the presentinvention are particles suitable for use in controlling odor oftenemanating from absorbent articles used for absorption of body fluidssuch as menses, blood, urine, and other excrements. Suitableodor-controlling particles include activated charcoal or active carbon,baking soda, chitin, deodorizing materials such as clays, diatomaceousearth, zeolites, and complexes of potassium permanganate with activealumina, used alone or in combination.

[0050] Various embodiments of the present invention also contemplateincluding particles to control air-borne and vapor-borne odors, as wellas including particulate material to slowly release a masking scent. Therelease of a masking scent can be achieved by using a superabsorbermaterial that slowly releases an incorporated scent, similar to themechanism by which superabsorbers slowly release moisture. As anexample, time release fragrances, using a fragrance adsorbed on aparticulate silica surface, can be incorporated in the meltblown web.Other deodorants and masking scents, also known in the art, which can beincorporated in particle form in the web, include the maladates,commonly known as chemical masking agents.

[0051] The amount of particles included in the meltblown web can dependon the particular use to be made of the web. In the present invention,particles may be added in any amount from a very minimum to an upperrange which would be the amount that would stay in the web withoutcausing the web to lose its integrity or the particles to undesirablydrop out of the web during handling. The particles may be about 0.1 toabout 80 percent, by weight, of the layer containing the particles.Generally, it is desired that the coform of any particular layer varybetween about 90 weight percent wood fibers and about 50 weight percentwood fibers and between about 10 weight percent meltblown fibers andabout 50 weight percent meltblown fibers for high absorbency and goodhandling properties.

[0052] In order to achieve a particular combination of properties in theweb, there are a number of variables in both the primary and secondarystreams that can be controlled along with the composition acid basisweight of the web. Process parameters susceptible to control in aprimary stream are the gas temperature, which is desirably in the rangeof about 600 to about 700° F. (about 315° C. to about 372° C.) withinthe ducts of the forming die; the gas volume, which is desirably in therange of about 250 to about 455 cubic feet per minute (about 118,000 toabout 215,000 cubic centimeters per second) within the ducts of theforming die; the polymer extrusion rate, which is desirably in the rangeof about 0.25 grams per hole per minute; the polymer temperature; andthe ratio of gas to polymer (mass flow rates) which is desirably in therange of about 10:1 to about 100:1. Variables that can be controlled ina secondary stream are the gas flow rate and the velocity of the pickerroll; the gas velocity which is desirably in the range of about 3,000 toabout 15,000 feet per minute (about 15 to about 76 meters per second);and the staple fiber size which is typically on the order of about 3millimeters in length. Variables that can be controlled in a tertiarystream include the gas temperature which is typically in the range ofabout 130 to about 390° F. (about 54 to about 200° C.), and desirablyabout 150 to about 300° F. (about 65 to about 150° C.); the gas volume,which is desirably in the range of about 5 to about 20 cubic feet perminute (about 2,400 to about 95,000 cubic centimeters per second); andthe particle size which is typically about 10 to about 350 microns indiameter. To minimize the likelihood of the meltblown fibers breakingupon impact of the particle, it is desired that the impact force (i.e.,the velocity and mass of the particle) be no greater than the tensilestrength (i.e., the maximum stress that a meltblown fiber can bearbefore it breaks or pulls apart, measured in force per unit of across-sectional area of the original meltblown fiber) of an individualmeltblown fiber. If desired, additional streams of gas can be similarlyadapted for use with the present invention.

[0053] The relationship between primary and secondary streams can alsobe controlled, and it is generally desired that the ratio of the gasvelocities in primary and secondary streams be in the range of about 5:1to about 10:1. The angle between primary and secondary streams at theirpoint of merger may also be varied, but it is generally desired to havethe two streams come together perpendicular to each other. Similarly,the particular point at which the two streams are merged, relative tothe die tip of the forming die in the upstream direction and the movingforming surface in the downstream direction, may be varied.

[0054] The relationship between a primary stream and a tertiary streamcan also be controlled, and it is generally desired that the ratio ofthe gas volumes in a primary stream and a tertiary stream be in therange of about 12:1 to about 90:1, depending, of course, on the size andmass of the particles. The angle between a primary stream and a tertiarystream at their point of merger may also be varied, but it is generallydesired to have the two streams come together perpendicular to eachother. Similarly, the particular point at which the two streams aremerged, relative to the die tip of the forming die in the upstreamdirection and the moving forming surface in the downstream direction,may be varied.

[0055] A tertiary stream having heated particles can merge into aprimary stream having meltblown fibers between the die tip of theforming die and the moving forming surface, provided that the heatedparticles can penetrate into the skin of one or more solidifyingmeltblown fibers upon impact. Thus, depending on the polymer, as well asthe meltblowing method conditions, the point of merger typically isabout 0 to about 2 inches (about 0 millimeters to about 51 millimeters)below the die tip. Desirably, the point of merger is about 0.5 to about1 inch (about 13 to about 25 millimeters) below the die tip. To minimizethe amount of residual heat lost by the particles to the environmentupon exit from the feeder duct of a particle supply unit, it is desiredthat the particles travel a distance of about 0 to about 1 inch (about 0to about 25 millimeters) upon exiting the feeder duct and merging with aprimary stream. It is even more desired that the particles travel adistance of about 0 to about 0.5 inch (about 0 to about 13 millimeters)upon exiting the feeder duct and merging with a primary stream.

[0056] The invention has been described with the formation of coformwebs. It is also within the invention to form successive layers ofgas-formed meltblown webs, not containing wood fibers or otheradditional staple fibers, in which the first layer is without particleswhile the second or other successive layer does contain particles. Inaddition, it is also within the, resent invention to form a single layergas-formed meltblown web, not containing wood fibers or other additionalstaple fibers, in which the single layer includes particles. Forexample, the forming apparatus as illustrated in FIG. 1 is capable offorming single-layer meltblown webs with particles if both the firstmeltblown unit 30 and the divellicating apparatus 152 of the secondmeltblown unit 130 are not operated. The phrases “meltblown layer” and“meltblown sheet”, as used herein, mean a gas-formed meltblown layer ofentangled meltblown fibers not containing staple fibers, whereas theterm “coform” is a layer, as previously described, that contains staplefibers in addition to meltblown fibers. Typically the gas used informing the gas-formed meltblown layers is air. Consequently, such aprocess is sometimes referred to as an air-forming or air-formed processwhich, in turn, typically produces one or more air-formed layers.

[0057] In an alternative embodiment, a layered web could be formed bythe illustrated apparatus of the drawings of FIGS. 1, 2 and 6 by notoperating the pulp sheet divellicating apparatus. In another alternativeembodiment, a structure of one or more coform layers in coherentintegral combination with one or more meltblown layers is also possible.Coform layers are desired over meltblown layers for most purposes ascoform layers are higher in absorbency. The formation of variouscombinations of meltblown layers and coform layers is within theinvention as is the placement of particles in either a meltblown layeror a coform layer.

[0058] A particle-containing web of the present invention finds uses ina variety of fields, depending, of course, on the particles employed.The web is particularly suitable for use in absorbent articles such asperineal shields and undergarments for the incontinent, bedpads,diapers, feminine hygiene products, and for body dressings such as thosefor wounds.

[0059] The novel method of the present invention renders the websubstantially nondusting. As a result of rendering the web substantiallynondusting, the web of the present invention advantageously may beeconomically die-cut into a variety of articles having predeterminedshapes with substantially no particles undesirably dropping out of thesides of either the web or the die-cut article. The ability to die-cutthe web enables the manufacturer to produce an absorbent article moreefficiently and economically, resulting in lower production costs whichcould be passed on to the consumer. A further advantage of rendering theweb substantially nondusting is that the die-cut absorbent articles neednot be subjected to tire additional step and expense of adding aperipheral seal to maintain the particles in the die-cut articles. Inaddition, certain embodiments of the web of the present invention havethe advantage that the particles will not be presented to a bodysurface.

[0060] As previously noted, depending on the type of particlesincorporated therein, the web of the present invention has a variety ofuses. For example, the material can be used in absorbent articles. FIGS.7 and 8 depict one embodiment of such an absorbent article. Theabsorbent article 450 of FIGS. 7 and 8 is formed with the absorbentmaterial of FIG. 3. The absorbent article 450 has an impervious polymerwrapping 454 and a body-side pervious member 452. The imperviouswrapping is adhered to the pervious liner by glue lines at 456 and 458.The ends of the absorbent article may be ultrasonically sealed at 460and 462. The coform material of layer 80 that does not have particulatematerial is exposed to the body of the wearer. The absorbent article 450may be utilized for absorption of any body exudate. Depending on thetype of particulate material used, typical uses of the absorbent articlewould include as incontinent devices, catamenial devices, diapers, orwound dressings.

[0061] Referring now to FIG. 9, another embodiment of an absorbentarticle is depicted. In FIG. 9, an absorbent article 610 is shown whichis designed to be worn by a woman to absorb body fluids such as menses,blood, urine, and other excrements. The absorbent article 610 can be asanitary napkin, a panty liner, a panty shield, an incontinent garment,or the like. A sanitary napkin is designed to absorb a greater quantityof fluid than a panty liner or panty shield. A sanitary napkin isusually longer, wider, and thicker than a panty liner and may contain asuperabsorbent or other type of material, such as peat moss, which canincrease its absorbent capacity. Sanitary napkins can have a length ofabout 6 to about 13 inches (about 152 to about 330 millimeters), a widthof about 2 to about 5 inches (about 51 to about 127 millimeters), and athickness of about 0.25 to about 25 millimeters. The sanitary napkin canhave a variety of shapes including rectangular, hourglass, oval, orracetrack.

[0062] Panty liners, on the other hand, are relatively thin and smalland can, but usually do not, contain a superabsorbent. A panty liner canhave a length of about 5 to about 10 inches (about 127 to about 25millimeters), a width of about 2 to about 3 inches (about 51 to about 76millimeters) and a thickness of about 1.3 to about 3.6 millimeters.

[0063] Incontinent garments are usually equal to or larger than sanitarynapkins. Incontinent garments can have a length of about 6 to about 33inches (about 152 to about 838 millimeters), a width of about 2.5 toabout 30 inches (about 64 to about 762 millimeters), and a thickness ofabout 19 to about 76 millimeters. Incontinent garments commonly have arectangular or an hourglass shape.

[0064] The absorbent article 610 can include a liquid-permeable cover612, a liquid-impermeable baffle 614, and an absorbent 616 positionedtherebetween. The cover 612 can be formed of a nonwoven material, suchas spunbond. The baffle 614 can be formed from a thin polyethylene film.The cover 612 and the baffle 614 can be eliminated, and the function ofthese two layers can be performed by other means. For example, the topsurface of the absorbent 616 can serve as the cover, and an adhesivecoating or a foam layer can replace the baffle.

[0065] The absorbent 616 has a body-facing surface and a garment-facingsurface. The absorbent 616 can be a hydrophilic material formed fromvarious types of natural or synthetic fibers including cellulose fibers,surfactant treated meltblown fibers, wood fibers, regenerated celluloseor cotton fibers, or a blend of pulp and other fibers. A desiredabsorbent material is the particle-containing coform material describedherein and formed with the forming apparatus of FIG. 1. A coform mixtureof about 70 percent wood fibers with about 30 percent polypropylenemeltblown fibers generally works well.

[0066] The absorbent can also contain thermoplastic polymers which canbe permanently deformed by the application of heat and pressure. Suchmaterials include polypropylene, nylon, polyethylene. polyesters. etc.Typical of such materials are bonded carded webs, meltblown and spunbondfabrics.

[0067] The cover 612, baffle 614, and absorbent 616 are sandwichedtogether to form a pad 618. The pad 618 includes a central portion 620with longitudinally-extendincg sides 622 and 624. The sides 622 and 6241can be either linear or non-linear so that the pad 618 can have variousconfigurations. For example, the pad 618 can have a rectangular, aracetrack, an hourglass, or an oval-shaped configuration.

[0068] It should be noted that the pad 618 has a uniform thicknessthroughout. This enables the pad 618 to be die-cut during manufacturefrom a large sheet of laminated material. In addition, the pad 618 couldoptionally have tabs as disclosed in U.S. Pat. No. 5,429,630, issuedJul. 4, 1995, to Beal et al., which is incorporated herein by reference.

[0069] The pad 618 can contain a plurality of embossed areas 630. InFIG. 9, the embossed areas 630 are shown as sinusoidal lines formedparallel to the longitudinal axis of the absorbent article 610. Theembossed areas can add integrity to the absorbent article 610 bysecuring the cover to the absorbent 616. The use of embossed lines givesan indication of ripples, or waves, which some consumers tend toassociate with fluid absorption. The embossed areas 630 can be evenlyspaced throughout the width of the absorbent article 610. The embossedareas 630 can also be in the form of dots, flowers, or the like.

[0070] The embossed lines 630 can be formed by running a laminatematerial through the nip of two rolls, the bottom roll being a pressureroll and the top roll being an embossing roll. The embossment will causethe cover 612 to be pinched down into the absorbent 616 and therebyassist the absorbent article 610 in being held together.

[0071] The pad 618 is formed out of a large sheet of laminate materialwhich includes a cover 612, baffle 614, and absorbent 616. The pad 618can be die-cut from this sheet of material and will have a body-facingsurface 632 and a garment-facing surface 634. The body-facing surface632 can be formed by the liquid-permeable cover 612, and thegarment-facing surface 634 can be formed by the liquid-impermeablebaffle 614.

[0072] Referring to FIG. 9, the absorbent article 610 further includesattachment means 636 secured to the garment-,acing surface 634. Theattachment means 636 can be a garment-attachment adhesive which providesa means for removably securing the pad 618 to the crotch portion of anundergarment, not shown. A garment attachment adhesive which works wellis adhesive NS34-5516 which is commercially available from NationalStarch Company located at 10 Finderne Ave., Bridgewater, N.J. 08807 Theattachment means 636 can include an adhesive 640 located on the centralportion 620. The particular design and configuration of the attachmentmeans 636 can vary.

[0073] Referring again to FIG. 9, the absorbent article 610 furtherincludes at least one piece of release paper 646 covering the attachmentmeans 636. The release paper 646 and the pad 618 can have coterminousexterior perpheries thereby facilitating a die-cut operation duringmanufacture. It is also possible to cut the release paper such that itcovers all of the adhesive but has a configuration which lies within theouter periphery of at least a portion of the pad 618. For example, therelease paper could run the length of the absorbent article 610, but benarrower than the overall width of the absorbent article 610. Therelease paper could also be cut larger than the pad 618, for example,having an outlying portion at one end so that the consumer could graspthe release paper and easily remove it from the pad 618.

[0074] The absorbent article 610 is designed to be die-cut from a sheetof laminate material including the cover 612, the baffle 614, theabsorbent 616, the attachment means 636, and the release paper 646. Thedie-cutting operation enables the manufacturer to produce the absorbentarticle 610 efficiently and economically. Lower production costscould-be passed on to the consumer.

[0075] Referring to FIG. 10, an absorbent article 648, such as asanitary napkin or panty liner is shown. The absorbent article 648 issimilar in construction to that discussed in FIG. 9, except that itincludes a continuous embossed line 650 formed about {fraction (1/64)}to about ½ inch (about 0.4 to about 13 millimeters) inward from theexterior periphery of the absorbent article 648. The embossed line 650provides integrity between the cover and the absorbent and isadvantageous in holding the article together when it is being removedfrom die crotch portion of an undergarment. The absorbent article 648has a racetrack configuration with a longitudinal axis designated X-Xand a transverse axis designated Y-Y. The absorbent article 648 alsocontains a plurality of sinusoidal embossed lines 652 which extendlengthwise across the absorbent article 648 with respect to thelongitudinal axis X-X. The embossed lines 652 do not extend beyond theperipheral embossed line 650. When the absorbent article 648 is asanitary napkin, it can have a surface area of less than about 30 squareinches (about 194 square 10 centimeters). Desirably, when the absorbentarticle 648 is a sanitary napkin, it has a surface area of less thanabout 25 square inches (about 161 square centimeters). When theabsorbent article 648 is a panty liner, the surface area can be lessthan about 20 square inches (about 129 square centimeters).

[0076] When the absorbent article is a sanitary napkin, it can have abasis weight of less than about 4100 grams per square meter, desirablyless than about 300 grams per square meter, and most desirably less thanabout 250 grams per square meter. For a panty liner, the basis weightcan be less than about 200 grams per square meter. Desirably, when theabsorbent article is a panty liter, it has a basis weight of less thanabout 190 grams per square meter; more desirably, less than about 170grams per square meter; and most desirably, less than about 150 gramsper square meter. For a panty liner containing particulate material, theparticulates can be incorporated in the meltblown web in amounts rangingfrom about 0.5 to about 30 grams per square meter, while the non-wovenabsorbent has a basis weight ranging from about 40 to about 350 gramsper square meter.

EXAMPLES

[0077] The following Examples describe various embodiments of theinvention. Other embodiments within the scope of the claims herein willbe apparent to one skilled in the art from consideration of thespecification or practice of the invention as disclosed herein. It isintended that the specification, together with the Examples, beconsidered exemplary only, with the scope and spirit of the inventionbeing indicated by the claims which follow the Examples. Parts,percentages and ratios are by weight unless otherwise indicated.

Example 1

[0078] Meltblowing Method Conditions:

[0079] Polymer Conditions:

[0080] Polymer: PRO-FAX® Polypropylene (polypropylene homopolymer,homopolymer pellets), Grade PF-015, commercially available from HimontIncorporated. Hercules Plaza, Wilmington, Del. 19894, USA

[0081] Temperature of Polymer at the Die Tip: approximately 510° F.(approximately 265° C.)

[0082] Die Tip Pressure: approximately 86 psig

[0083] Air Gap in the Ducts of the Formina Die: 18 to 20 thousandths ofan inch

[0084] Average Temperature of Air in the Ducts of the Forming Die:approximately 565° F. (approximately 296° C.)

[0085] Particle Conditions:

[0086] Particles: 85% Baking Soda and 15% ABSCENTS® 5000 (ABSCENTS® 5000is an odor-controlling particle commercially available from UOP LLC, 25East Algonquin Road, P.O. Box 5017, Des Plains, Ill. 60017, USA). Theparticles had a size range of about 5 to about 300 microns in diameter.

[0087] Exit Temperature of Tertiary Stream: approximately 155° F.(approximately 68° C.)

[0088] Gas Volume of Tertiary Stream: approximately 20 cubic feet perminute (approximately 95,000 cubic centimeters per second)

[0089] Pulp/Polymer Ratio: 70/30

[0090] Coform Only: 170 grams per square meter

[0091] The method described above resulted in the ABSCENTS® 5000particles being incorporated in the meltblown web in a predeterminedamount of about 2 to about 3 grams per square meter.

Example 2

[0092] Example 2 utilized the same Meltblowing Method Conditions asExample 1, except that the only particles present were ABSCENTS® 5000.The particles had a size range of about 20 to about 300 microns indiameter. The method described herein resulted in the particles beingincorporated in the meltblown web in a predetermined amount of about 2to about 3 grams per square meter.

Example 3

[0093] Example 3 utilized the same Meltblowing Method Conditions asExample 1, except that the only particles present were ABSCENT® 3000, anodor-controlling particulate, commercially available from UOP LLC. Theparticles had a size range of about 5 to about 25 microns in diameter.The method described herein resulted in the particles being incorporatedin the meltblown web in a predetermined amount of about 2 to about 3grams per square meter.

Example 4

[0094] Meltblowing Method Conditions:

[0095] Polymer Conditions:

[0096] Polymer: ESCORENE Polypropylene (granular resin), Grade PD 3505G,commercially available from Exxon Chemical Company, 13501 Katy Freeway,Houston, Tex. 77079-1398, USA

[0097] Temperature of Polymer at the Die Tip: approximately 521° F.(approximately 272° C.)

[0098] Die Tip Pressure: approximately 83 psig

[0099] Air Gap in the Ducts of the Forming Die: 18 to 20 thousandths ofan inch

[0100] Average Temperature of Air in the Ducts of the Forming Die:

[0101] approximately 570° F. (approximately 299° C.)

[0102] Particle Conditions:

[0103] Particles: Bakin, Soda. The particles had a size range of about 5to about 350 microns in diameter.

[0104] Exit Temperature of Tertiary Stream: approximately 165° F.(approximately 74° C.)

[0105] Gas Volume of Tertiary Stream: approximately 20 cubic feet perminute (approximately 95,000 cubic centimeters per second)

[0106] Pulp/Polymer Ratio: 70/30

[0107] Coform Only: 170 grams per square meter

[0108] The method described above resulted in the particles beingincorporated in the meltblown web in a predetermined amount of about 2to about 3 grams per square meter.

Example 5

[0109] Example 5 utilized the same Meltblowing Method Conditions asExample 4, except that the only particles present were ABSCENTS® 5000.The particles had a size range of about 20 to about 300 microns indiameter. The method described herein resulted in the particles beingincorporated in the meltblown web in a predetermined amount of about 2to about 3 grams per square meter.

Example 6

[0110] Meltblowing Method Conditions:

[0111] Polymer Conditions:

[0112] Polymer: Polypropylene (granules), Grade PD 3485, commerciallyavailable from Exxon Chemical Company

[0113] Temperature of Polymer at the Die Tip: approximately 519° F.(approximately 271° C.)

[0114] Die Tip Pressure: approximately 85 psig

[0115] Air Gap in the Ducts of the Forming Die: 18 to 20 thousandths ofan inch

[0116] Average Temperature of Air in the Ducts of the Forming Die:

[0117] approximately 571° F. (approximately 299° C.)

[0118] Particle Conditions:

[0119] Particles: 85% Baking Soda and 15% ABSCENTS® 5000. The particleshad a size range of about 5 to about 300 microns in diameter.

[0120] Exit Temperature of Tertiary Stream: approximately 155° F.(approximately 68° C.)

[0121] Gas Volume of Tertiary Stream: approximately 20 cubic feet, perminute (approximately 95,000 cubic centimeters per second)

[0122] Pulp/Polymer Ratio: 70/30

[0123] Coform Only: 170 grams per square meter

[0124] The method describe, above resulted in the ABSCENTS® 5000particles being incorporated in the meltblown web in a predeterminedamount of about 2 to about 3 grams per square meter.

Example 7

[0125] Example 7 utilized the same Meltblowing Method Conditions asExample 6, except that the oily particles present were ABSCENTS® 5000.The particles had a size range of about 20 to about 300 microns indiameter. The method described herein resulted in the particles beingincorporated in the meltblown web in a predetermined amount of about 2to about 3 grams per square meter.

Example 8

[0126] Example 8 utilized the same Meltblowing Method Conditions asExample 6, except that the only particles present were ABSCENTS® 3000from UOP LLC. The particles had a size range of about 5 to about 25microns in diameter. The method described herein resulted in theparticles being incorporated in the meltblown web in a predeterminedamount of about 2 to about 3 grams per square meter.

[0127] In view of the foregoing, it will be seen that the severaladvantages of the invention are achieved and other advantageous resultsattained.

[0128] As various changes could be made in the above methods andmeltblown webs without departing from the scope of the invention, it isintended that all matter contained in the foregoing description andshown in the accompanying drawings shall be interpreted as illustrativeand not in a limiting sense.

I claim:
 1. A method of forming a meltblown web, the method comprising:(a) forming at least one layer by the steps of: (i) forming a firstprimary stream containing meltblown fibers; (ii) forming a firstsecondary stream comprising staple fibers; (iii) merging the firstprimary stream and the first secondary stream so that the first primarystream comprises the staple fibers entangled with the meltblown fibers;and (iv) thereafter directing the first primary stream comprising thestaple fibers entangled with the meltblown fibers onto a moving formingsurface to form a first layer comprising the staple fibers entangledwith the meltblown fibers; (b) forming at least one particle-containinglayer by the steps of: (i) forming a second primary stream containingmeltblown fibers; (ii) forming a first tertiary stream comprisingparticles; (iii) merging the second primary stream and the firsttertiary stream so that the second primary stream comprisesparticle-containing, meltblown fibers; (iv) forming a second secondarystream comprising staple fibers; (v) merging the second primary streamcomprising particle-containing meltblown fibers and the second secondarystream so that the second primary stream comprises the staple fibersentangled with the particle-containing meltblown fibers; and (vi)thereafter directing the second primary stream comprising the staplefibers entangled with the particle-containing meltblown fibers onto thefirst layer on the moving forming surface to form a second layercomprising the staple fibers entangled with the particle-containingmeltblown fibers.
 2. The method of claim 1, further comprising formingat least one additional layer by the steps of: (a) forming a thirdprimary stream containing meltblown fibers; (b) forming a thirdsecondary stream comprising staple fibers; (c) merging the third primarystream and the third secondary stream so that the third primary streamcomprises the staple fibers entangled with the meltblown fibers; and (d)thereafter directing the third primary stream comprising the staplefibers entangled with the meltblown fibers onto the second layer on themoving forming surface to form a third layer comprising the staplefibers entangled with the meltblown fibers.
 3. The method of claim 1,further comprising forming at least one additional particle-containinglayer by the steps of: (a) forming a third primary stream containingmeltblown fibers; (b) forming a second tertiary stream comprisingparticles; (c) merging the third primary stream and the second tertiarystream so that the third primary stream comprises particle-containingmeltblown fibers; (d) forming a third secondary stream comprising staplefibers; (e) merging the third primary stream comprisingparticle-containing meltblown fibers and the third secondary stream sothat the third primary stream comprises the staple fibers entangled withthe particle-containing meltblown fibers; and (f) thereafter directingthe third primary stream comprising the staple fibers entangled with theparticle-containing meltblown fibers onto the second layer on the movingforming surface to form a third layer comprising the staple fibersentangled with the particle-containing meltblown fibers.
 4. The methodof claim 1, wherein the particles are heat-stable particles.
 5. Themethod of claim 4, wherein the tertiary stream comprising particles hasa temperature of about 50 to about 200° C.
 6. The method of claim 4,wherein the tertiary stream comprising particles has a temperature ofabout 65 to about 150° C.
 7. The method of claim 3, wherein theparticles are heat-stable particles.
 8. The method of claim 7, whereineach tertiary stream comprising particles has a temperature of about 50to about 200° C.
 9. The method of claim 7, wherein each tertiary streamcomprising particles has a temperature of about 65 to about 150° C. 10.The method according to claim 1, 2 or 3 wherein the staple fibers arewood fibers.
 11. A method of forming a meltblown web, the methodcomprising forming at least one layer by the steps of: (a) forming aprimary stream of meltblown fibers; (b) forming a tertiary streamcomprising particles; (c) merging the primary stream and the tertiarystream so that the primary stream comprises particle-containingmeltblown fibers; and (d) thereafter directing the primary streamcomprising particle-containing meltblown fibers onto a moving formingsurface to form a layer comprising the particle-containing meltblownfibers.
 12. The method of claim 11, wherein the particles areheat-stable particles.
 13. The method of claim 12, wherein the tertiarystream comprising particles has a temperature of about 50 to about 200°C.
 14. The method of claim 12, wherein the tertiary stream comprisingparticles has a temperature of about 65 to about 150° C.
 15. A method offorming a meltblown web, the method comprising forming at least onelayer by the steps of: (a) forming a primary stream containing meltblownfibers; (b) forming a tertiary stream comprising particles; (c) mergingthe primary stream and the tertiary stream so that the primary streamcomprises particle-containing meltblown fibers: (d) forming a secondarystream comprising staple fibers; (e) merging the primary streamcomprising particle-containing meltblown fibers and the secondary streamso that the primary stream comprises staple fibers entangled with theparticle-containing meltblown fibers; and (f) thereafter directing theprimary stream comprising the staple fibers entangled with theparticle-containing meltblown fibers onto a moving forming surface toform a layer comprising the staple fibers entangled with theparticle-containing meltblown fibers.
 16. The method of claim 15,wherein the particles are heat-stable particles.
 17. The method of claim16, wherein the tertiary stream comprising particles has a temperatureof about 50 to about 200° C.
 18. The method of claim 16, wherein thetertiary stream comprising particles has a temperature of about 65 toabout 150° C.
 19. The method of claim 15, wherein the staple fibers arewood fibers.